It happens in track and field, too. The difference is, less money and more risk. Too often, those who flee the structure of a college program find their careers regressing and soon ending.

"People who know the sport know that this is just wrong, what's happening with kids leaving school early," Illinois women's coach Tonja Buford-Bailey said.

That's why she has advised Ashley Spencer, a sophomore sprinter from Indianapolis, to retain college eligibility. Spencer, 20, who has won two NCAA 400-meter titles and two world junior (under-20) gold medals, has been targeted by agents even before this week's USA Championships in Des Moines.

Spencer's time of 50.28 seconds ranks No. 5 in the world and No. 4 in the nation. She is No. 3 among entries and in position not only to make the U.S. team but to win medal at the World Championships in Moscow in August.

This will be Spencer's first USA nationals and first races against pros. But she has never lost head-to-head in a 400 final, and she has won 13 consecutive outdoor 400s. The first heats of the 400 are scheduled for Thursday in Des Moines.

"I really want to do all four years of college, get my degree and all that," Spencer said. "I want to have the entire college experience before going pro. There's really no need to rush it."

Two of her peers, Oregon sprinter English Gardner and Clemson hurdler Brianna Rollins, recently gave up their remaining eligibility and declared themselves pros.

That might work for them. It has not worked for Candyce McGrone, another Indianapolis high school product who went pro after winning an NCAA 100-meter title in 2011 for Oklahoma. McGrone has qualified for these nationals but has trouble getting into meets and has not run as fast as she did in college.

The coach said agents leave Spencer alone because she knows them, and they know her. Buford-Bailey, 42, was a three-time Olympian in the 400 hurdles and won an Olympic bronze medal in 1996.

"They know not to mess with me, she said.

Buford-Bailey said veteran coach Brooks Johnson, 78, spoke to Spencer briefly and came away convinced that the sprinter is happy with what she is doing. She is having fun, Johnson told the coach, and track is not fun.

"And I hate to say it, but at the level past college — and I've been at that level, it's great, it's your dream, it's a way to make a living, it's fulfilling because you get accomplishments like Olympic medals when you're good — but it's not fun," Buford-Bailey said. "Being on a plane every weekend, traveling and going to countries where you don't know people and your coach not being there. It's totally different."

Spencer and her coach made the controversial decision to bypass last year's Olympic trials — and thus a potential London spot — and concentrate on world juniors. It was another example of what Spencer calls "baby steps."